Ida takes aim at the U.S. Gulf Coast

Hurricane Ida burst into the Gulf of Mexico as a Category 2 hurricane with 100 mph winds this afternoon, and is poised to deliver a solid blow to the U.S. Gulf Coast between Southeast Louisiana and the Florida Panhandle on Tuesday morning. Radar imagery out of Cancun reveals that Ida has retained its tight inner core this afternoon, with only limited rain bands affecting Mexico and western Cuba. Top winds at Cancun, Mexico today were only 15 mph, despite the fact that Ida passed just 60 miles east of the city. Infrared and visible satellite loops show little change in the intensity of Ida's heavy thunderstorms this afternoon, but the cloud pattern is beginning to become distorted due to strong upper-level winds from the southwest that are creating 20 - 25 knots of wind shear over the hurricane. Water vapor satellite imagery reveals a large area of dry air to the southwest of Ida, but this dry air has not yet intruded into Ida's core. The latest 5:30 pm EST vortex report from the Hurricane Hunters showed that the central pressure had risen 1 mb, to 977 mb, but that the surface winds were still near 100 mph. They noted that the eyewall was open to the east, a sign that Ida's inner core may be in trouble.

The intensity forecast for IdaThe high wind shear of 20 - 25 knots currently affecting Ida is forecast to persist at that level until Monday night. With the storm now beginning to show a distortion of the cloud pattern due to this shear, it would not be a surprise of the shear managed to inject some dry air into Ida's core Monday morning, significantly weakening the storm. Aiding this process will be cooler waters. Early Monday morning, Ida will be crossing over waters of 26°C, which is barely enough to support a hurricane. By Monday night, wind shear is expected to increase to 40 knots, which ordinarily would begin to tear the storm apart. This wind shear is due to an extratropical low pressure system over the western Gulf of Mexico, and this low will begin dumping cold, stable air into Ida Monday night through Tuesday. This will cause Ida to begin transitioning to an extratropical storm, and it is possible that during the transition Ida's winds will die down relatively slowly, despite the wind shear. The intensity forecast has a high amount of uncertainty, and I wouldn't be surprised at a landfall strength anywhere in the range of 45 mph - 80 mph. My personal best guess is a 50 - 60 mph tropical storm at landfall. Regardless of Ida's strength at landfall, the storm will be able to dump 4 - 8 inches of rain along the Gulf Coast, from New Orleans to Panama City. Isolated tornadoes will also be possible, primarily to the right side of Ida's track.

Figure 2. Maximum storm surge (depth of water above ground) for a Category 1 hurricane with 85 mph winds moving north-northeast at 15 mph. Ida is expected to be moving at this speed and direction at landfall, but will probably be weaker, so surges will not be this high. Image credit: NOAA SLOSH model run for Mobile Bay, 2008 version. Heights are given relative to the NAVD88 datum.

The storm surge forecast for IdaStorm surge is the other major concern for Ida. With a strong high pressure system anchored over the U.S. today, the pressure difference between this high and Ida is creating a strong pressure gradient that will drive tides 3 - 5 feet above normal from New Orleans to the Florida Panhandle tonight. As Ida approaches on Monday, an additional rise in water will occur, and a large stretch of coast will be subject to very high water levels for an extended period of time. With battering waves building Monday afternoon into Tuesday morning, a significant coastal erosion event is shaping up. A particular concern is the western end of Alabama's Dauphin Island, where storm surges from four hurricanes over the past fifteen years have caused heavy damage to the low-lying heavily developed island. If Ida makes a direct hit on Mobile Bay as a Category 1 hurricane with 85 mph winds, a storm surge of up to six feet is possible there, assuming the storm hits at mean tide. The tidal range along the Gulf Coast varies by about 1.5 feet between low and high tide (Figure 3). High tide is near 2 am EST on Tuesday, but the official NHC forecast currently has the storm hitting between 6 am - 9 am, when the tide will be going out, so the storm may indeed be hitting at about mean tide.

Figure 3. The tide forecast for the Gulf Coast calls for high tide to occur around 2 am EST Tuesday morning. Ida is expected to hit later that morning, while the tide is going out.

A HURRICANE WARNING REMAINS IN EFFECT FOR THE NORTHERN GULF COASTFROM PASCAGOULA MISSISSIPPI EASTWARD TO INDIAN PASS FLORIDA. AHURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTEDSOMEWHERE WITHIN THE WARNING AREA WITHIN 24 HOURS. PREPARATIONS TOPROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION.

A TROPICAL STORM WARNING AND A HURRICANE WATCH REMAIN IN EFFECT FORTHE NORTHERN GULF COAST FROM GRAND ISLE LOUISIANA EASTWARD TO WESTOF PASCAGOULA MISSISSIPPI...INCLUDING NEW ORLEANS AND LAKEPONTCHARTRAIN. A TROPICAL STORM WARNING MEANS THAT TROPICAL STORMCONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 24HOURS. A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS AREPOSSIBLE WITHIN THE WATCH AREA...IN THIS CASE WITHIN 24 HOURS.

A TROPICAL STORM WARNING REMAINS IN EFFECT FOR THE NORTHERN GULFCOAST FROM EAST OF INDIAN PASS FLORIDA TO AUCILLA RIVER FLORIDA.

AT 300 AM CST...0900 UTC...THE CENTER OF HURRICANE IDA WAS LOCATEDNEAR LATITUDE 25.1 NORTH...LONGITUDE 87.9 WEST OR ABOUT 285 MILES...460 KM...SOUTH-SOUTHEAST OF THE MOUTH OF THE MISSISSIPPI RIVER ANDABOUT 375 MILES...605 KM...SOUTH OF PENSACOLA FLORIDA.

IDA IS MOVING TOWARD THE NORTH-NORTHWEST NEAR 16 MPH...26 KM/HR. ATURN TOWARD THE NORTH AND AN INCREASE IN FORWARD SPEED ARE EXPECTEDDURING THE NEXT 24 HOURS...FOLLOWED BY A TURN TOWARD THE NORTHEASTON TUESDAY. ON THE FORECAST TRACK...IDA IS EXPECTED TO MOVE ACROSSTHE GULF OF MEXICO TODAY...AND APPROACH THE NORTHERN GULF COASTTONIGHT OR EARLY TUESDAY.

DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATETHAT MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 90 MPH...150KM/HR...WITH HIGHER GUSTS. IDA IS A CATEGORY ONE HURRICANE ON THESAFFIR-SIMPSON SCALE. ADDITIONAL WEAKENING IS FORECAST DURING THENEXT 24 HOURS. HOWEVER...IDA IS STILL EXPECTED TO BE A HURRICANEWHEN IT APPROACHES THE GULF COAST TONIGHT OR EARLY TUESDAY.

THE ESTIMATED MINIMUM CENTRAL PRESSURE BASED ON DATA FROM THEHURRICANE HUNTER AIRCRAFT IS 988 MB...29.18 INCHES.

RAINS WILL BE INCREASING WELL IN ADVANCE OF IDA ACROSS THE CENTRALAND EASTERN GULF COAST...BUT WILL BECOME STEADIER AND HEAVIERLATER TODAY INTO TUESDAY. TOTAL STORM ACCUMULATIONS OF 3 TO 6INCHES WITH ISOLATED MAXIMUM STORM TOTALS OF 8 INCHES WILL BEPOSSIBLE THROUGH TUESDAY FROM THE CENTRAL AND EASTERN GULF COASTNORTHWARD INTO THE EASTERN PORTIONS OF THE TENNESSEE VALLEY AND THESOUTHERN APPALACHIANS.

A DANGEROUS STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 4 TO 6FEET ABOVE GROUND LEVEL ALONG THE COAST NEAR AND TO THE EAST OFWHERE THE CENTER MAKES LANDFALL. NEAR THE COAST...THE SURGE WILL BEACCOMPANIED BY LARGE AND DESTRUCTIVE WAVES.

Patrap...your loop confirms that she is severly de-coupled. I understand why the Hurricane Hunters are finding the steep rise in pressure. I thought she'd actually turn into the shear and make it steer. She did at the mid levels. That mid-level circulation is headed for Tampa. The storm tops are still blowing off the the SW from the center, which has been something pretty amazing to me through the life of this storm. Overshooting cloud tops are apparently facing a differential flow.

Quoting jpritch:homeless, yes, the coc is clearly well west of the forecast track. It's a race at this point. At the speed it's going, it has a good chance of sliding a bit farther west before it gets turned north.

Oh thank goodness I wasn't imagining it. :) Looked like it missed its points to me too. I agree about the race. But I can't believe LA is not in the cone at least.

Quoting emguy:KoritheMan...she hasn't made landfall yet...and she's probably not going to be a cane when she does. Sounds like these stats may hold on for another day.

Yeah, I'm not actually expecting her to make landfall at hurricane intensity. I've analyzed this storm very closely, and from what I see, I think she'll landfall as a 55 kt (65 mph) storm.

Still though, even if the hurricane force sustained winds subside prior to landfall, gusts to hurricane force will still be possible in the heavier squalls. Additionally, extratropical transition typically means a broadening of the wind field.

1, We've had pretty steady easterly winds here this weekend due to the pressure gradient between us and Ida. We've also had mostly overcast skies and lower temps all weekend, a welcome change from last week's summer-like temperatures.

2, This has been an unusual year. Just when everybody thought the season was just about done, up pops this Ida, a persistent storm that seems determined to defy convention.

Quoting Fshhead:HAHAHAHAHAHAHA!!!!!Man I was lurkin here earlier today & they were all swearing it was turning towards the East. Always trying to outthink the NHC. Ummm think I will take the NHC over some blogger any day!!Sooooo I think quite a bit of crow is on the menu.. ;)

Hi, glad to see there's a few people up, hi, x-cool - I crashed on couch, just woke up, I'm kind of out of it, blurry-eyed...it's 3 am here and I'm not going to be able to stay awake 'til 4. Where are we, I see it's a Cat 1 now. May I have a quick update, pls.? Is landfall supposed to be in Mobile area?

HAHAHAHAHAHAHA!!!!!Man I was lurkin here earlier today & they were all swearing it was turning towards the East. Always trying to outthink the NHC. Ummm think I will take the NHC over some blogger any day!!Sooooo I think quite a bit of crow is on the menu.. ;)

I've been planning to go fishing today in Manchac, LA. With the rain and wind I probably gonna chicken out though. The fish really bite when the pressure starts dropping though. I might still give it a try when Ida starts her turn to the NE. Looks like she is falling apart pretty fast.

Quoting Fshhead:Its supposed to be time to focus on Turkeys & X-Mas, not a freaking hurricane. LOL

Tell me about it. o_O

This is the first time, to my knowledge, that a hurricane has made United States landfall in November during an El Nino year since 1925, and the first time a hurricane has struck the United States in November since 1985's Hurricane Kate.

Evening Pat & Everyone else!!You would think Ida is close to Miami & stronger, its real breezy here. Sure glad she is winding down some. Its supposed to be time to focus on Turkeys & X-Mas, not a freaking hurricane. LOL